Method and apparatus for the chemical treatment of pulp



1931. c. R. VAN DE CARR, JR 1,818,913

METHOD AND APPARATUS FOR THE CHEMICAL TREATMENT OF PULP Filed April 12. 1928 PulpDigesler INVENTOR. Charles Van de Carr J21 vhf 6 ATTOR EY.

Patented Aug. 11, 1931 UNITED STATES PATENT OFFICE OHABLESB. VAN n1: CARR, JB., OI DAYTON, OHIO, ASSIGiOR TO cmnwr-r PBOGII', 1110., WATERTOWH, NEW YORK, A CORPORATION OI m YO METHOD AND APPARATUS FOR THE CHEMICAL rmmmr OI rm Application fled April 13, 1888. semi I0. 9,4.

This invention relates to the treatment of fibrous material, and more particularly to a novel method and apparatus for the chemical treatment of pu I In the digestion of fibrous material with chemical liquors, it is customary in unloading the digesters, to permit the same to blow directly into a blow-pit. This has disadvantages well known to those skilled in the art. It is my idea to pump the cooked Eglp from a digester, after the pressure has en relieved from the latter, and to pass this ulp through a continuous washing recess. Tn doing this, it will be found that t e pulp in the d1gester, after some of the liquor has been withdrawn, will compact at the discharging end of the digester, to such a degree that the pump cannot ull the ulp out of the digester. In accor ance wit my invention, I overcome this difiiculty by forcing spent liquor from the washer into one or the other or both ends of the digester for d1lut ing the pulp mass and putting the same into fluid condition. $5 The primary object of the invention 1s to provide an improved system for the unloading of digesters without resorting to the ordinary blow pits, and in this system the pulp is withdrawn from the digesters by means of a pump which may force the same dlrectly to' a washer, or into a pulp storage tank, from which the pulp may pass through a ulpbreaker, on its way to the washer. gpent liquor from the washer is wlthdrawn by another pump and may be forced by the latter into one or both ends of the dlgester for diluting the pulp, so that it will readily flow from the digester.

With the foregoing object outlmed and 40 with other objects in view which will appear as the description proceeds, the invention consists in the novel features hereinafter described in detail, illustrated in the accompanying drawing, and more particularly pointed out in the a pended claims.

Referring to the wmg, the figure 1s a diagrammatic view of an apparatus for use in carryin out my process. In the rawing, A des1gnates a pulp d1- '0 gester, B a pulp pump, 0 a pulp storage tank,

-rotation,'and un er such clrcumstanoes, the

D a pulpl breaker, E a vacuum washer and F a spent 'quor pump. These arts are all of standard construction, but I ave combined the same in a novel manner. In my system, the pulp in moist condition, after the coo is completed, is withdrawn throu h a valv pipe A by meansof the pump and it is orced by the latter through a conduit B ing: tlie storage tGa nk C. hIt led from 3e a or ya ipe intot e rum-typep p breaker D, roin which it flows by a pipe D into the vacuum washer E.

As heretofore mentioned the ulp is liable to pack in the lower end of the isester during the unloading of the latter an thus halt operations, and to eliminate this objection, I withdraw spent liquor from the washer, b way of pipe E',; into the pum F, whic forces the same thro h a con uit F into valved branches F an F; the first branch leading to the to of the digester, and the other branch lea inginto the lower portion of the digester or pipe A.

In this way, the s nt liquor may be used to keep the ulp in uid condition, so that it ma be rea ily withdrawn by the pump B.

en the invention is used in connection with a battery of digesters, it will be understood that the di esters may be unloaded in U washer may be continuously operated, and

there will always be suflicient pulp in the storage tank 0 to feed the washer.

The ent liquor withdrawn from the washer is the li uor with which the pulp has been cooked. t the end cookin point, the li nor has been drawn from the 'gester in cient amount to reduce the pulp density from 3 to 10%; then the vacuum washer further reduces the densi to about 30%, but at a 10% density insi e the digester, it is impossible to make the pulp ow; eonse uently, I propose to use a percentage of t e spent liquor from the vacuum washer as an agent to dilute the pulp in the di ester.

ere will be times during the operation of the system when it will be unnec to feed the spent liquor or diluting fluid into the digester, and at such times, the fluid may 10' be discharged from the vacuum was her It may also be advantageous at certain times during the unloading of the digester to dilute the ulp mass bymeansof water or any other smtable anti-acid liquid, and for th1 s purpose, such liquid ma be introduced into the system through a va ved pipe H. A bleaching agent can also be introduced through the pipe H, so as to dilute-the pulp by means of a bleachin agent, and for the further purpose of preleaching.

From the foregoing, it is believed that the construction and operation of the apparatus, and the steps of the process may be clearly understood, and I am aware that changes may be made in the details disclosed without departin'gfrom the spirit of the invention as expressed in the claimsv What I claim and desire to secure by Letters Patent is:

1. In the treatment of ulp, digesting fibrous material and wit drawing pulp from the digester, washing said pulp, and feeding s ent'liquor from the washer into the; pulp caving the digester to dilute said pu p. c

2. In pulp treatment, digesting fibrous material, discharging the material from the digester, washing the material, and feeding some of the washing fluid from the washer into the digester for diluting the material in the latter.

3. In a process of the character described, cooking fibrous material in a digester with chemical liquor, pumping said fibrous material from the digester, feeding the withdrawn material into a washer and washing the same, and feeding the spent liquor from the washer into the digester for diluting the material in the latter while it is being withdrawn from the digester.

4. In a process of the character described, cooking fibrous material with chemical liquor in a digester, pumping the material from the lower end of the digester, washing the material discharged from the digester, and feeding spent liquor from the washer to the upper and lower ends of the digester for diluting the material while it is being discharged from the digester.

5. In a process of the character described, cooking fibrous material with chemical liquor, pumping the material from the digester after the completion of the cooking, breaking the material discharged from the digester, washing the broken material, and feedin rial while it is being discharged from the igleigg islter for the purpose of diluting said ma- 6. A pulp treating apparatus,

. comprismg a digester, a washer,

means mcluding a pump for withdrawing pulp from. the digester and feeding the same to the washer, and means for feeding spent liquor from the washer into the digester.

7. An apparatus of the class described, comprising a digester, a washer, a passage way placing thev digester in commumcatlon with the washer for feeding pulp from the digester to the washer, and means including r for feeding the same into the washer, and

means including a pump for forcing spent liquor from the washer into the upper and lower portions of the digester.

10. In combination, a digester, a washer, pulp conveying means including a pump for withdrawing pulp from the digester and feeding the same to the washer, a conduit for feeding spent liquor from the washer, a pump interposed in said conduit, and branch pipes connecting the conduit to the opposite ends of the digester.

11. In combination, a pulp treating digester, a pipe leading from the lower end of the same, a pump connected to the pipe for withdrawing pulp from the digester, a pulp washer, means including a pipe for feeding pulp from the pump to the washer, a conduit connecting the first mentioned pipe to the washer for conveying spent liquor from the washer into the first mentioned pipe, and a pump interposed in said conduit.

'12. A combination as claimed inclaim 11, including a pipe connecting said conduit to the upper end of the digester.

13. In combination, a digester, a pul storage tank, a conduit connecting the di: gester to the storage tank, a pump interposed in said conduit, a pulp breaker, means for leading pulp from the tank to said breaker, a pulp washer, means for leading pulp. from the breaker to the washer, and means including a pump for feeding spent liquor from the washer into the digester.

14. A pulp treating apparatus, comprising a digester, means including a pump for withg drawing pulp from the digester, andemeans spent liquor from the washer mto the matef or pumping a diluting fluid into the digester while the material is being pumped from the same.

15. In pulp treatment, digesting fibrous I material, simultaneously pumping the material and cooking liquor from the digester after the ressure has been released from the latter, an introducing a diluting liquid into the material and cooking liquor anterior to the pump while discharging the material and cooking liquor from the digester. V

16'. In a process of the character described,

.cooking fibrous material in a digester with 

